How do you create opaque liquid?
For materials such as milk, latte or hot chocolate, the use of Subsurface Scattering is a good choice. It allows the light to enter the solid material, scatter around, and exit at another point. The material is not transparent but still opaque.
The liquid in the following example has a subsurface scattering of 0.055, base color and subsurface color are the same (hex: 835842), Subsurface Radius is (1.0, 0.75, 0.5), no transmission (glass), unchanged alpha (1.0=no transparency).
The Bump map is from the tutorial video &quot;How to Make Milk in Blender EEVEE&quot; (https://youtu.be/Hzpmz683xsw). It adds a very subtle distortion of the reflections on the surface.

Milk shader setup: